This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. xc2xa7119 from an application entitled STATE TRANSITION METHOD IN MOBILE COMMUNICATION SYSTEM earlier filed in the Korean Industrial Property Office on Apr. 25, 1998, and there duly assigned Ser. No. 98-14880.
1. Field of the Invention
The present invention relates generally to a mobile communication system, and in particular, to a method for arbitrating a power level between a base station and a mobile station in a CDMA mobile communication system.
2. Description of the Related Art
An existing code division multiple access (CDMA) mobile communication system mainly supports voice service. It is, however, foreseeable that mobile communications will be performed in accordance with the IMT-2000 (International Mobile Telecommunication-2000) standard in the near future. The IMT 2000 standard provides not only voice service but also high speed packet service. For example, the IMT-2000 standard supports high quality voice service, moving picture service, Internet search service, etc.
In the existing CDMA mobile communication system, after completion of data transmission, a channel used for data transmission is released. Thereafter, when there is a need to restart data transmission, the channel is reconnected in response to a channel request message to transmit the data. However, due to the channel reconnection, the existing system has an increased time delay in providing the packet service as well as the voice service, so that it is difficult to provide a high quality service. Therefore, there is a demand for an improved method capable of providing the packet service with reduced time delay. If there is a discontinuous transmission (DTX) data channel, a burst data is transmitted intermittently. In the packet data service, after transmission of the burst data, there is a non-transmission interval before transmission of the next burst data. In the non-transmission interval, the existing system releases or maintains the channel; releasing the channel causes a time delay in reconnecting the channel and maintaining the channel results in a waste of channel resources and an increase of undesired interference to other channels.
It is, therefore, an object of the present invention to provide a power control method for transitioning from a state where data is not transmitted to a state where data can be immediately transmitted, in a mobile communication system.
It is another object of the present invention to provide a method for transitioning from a slotted substate to a normal substate where a transition to an active state can be readily made.
It is further object of the present invention to provide a method for efficiently controlling the transmission power of a base station and a mobile station in a mobile communication system.
The present invention is directed specifically to the case of slotted substate. However, the invention has general application to all DTX channels in a CDMA mobile communication system including the IMT-2000 system. For example, where the DTX channel is a DCCH (dedicated control channel) and a SCH (supplemental channel). The DCCH is used in a control hold state and an active state (data transmission state) and SCH is used only in an active state. Both channels can transmit messages discontinuously. In the cases of a DTX channel that has no data to transmit, a power control signal is transmitted. However, the time between message transmissions may be long. Moreover, the process of (channel releases has an associated time delay and continuous transmissions can increase interference). Therefore the present invention has applicability to the entire DTX channel including DCCH and SCH, which maintain a period of non-transmission with no power control.
To achieve the above objects, a mobile communication system according to the present invention controls the transmission power of radio links between a base station and a mobile station. The method of the present invention includes (1) assigning forward and reverse dedicated control channels to the base station and the mobile station, respectively, and controlling transmission power of the forward and reverse dedicated control channels so that the respective channels can receive data; (2) discontinuing the transmission power control, when data to be transmitted is not generated for a predetermined time; and (3) performing power level arbitration which involves re-controlling the transmission power of the forward and reverse DTX channels in a state where the transmission power control has been discontinued (see step 2), to adjust the transmission power so that the respective channels can transmit/receive data again.